Isolation valves

ABSTRACT

Isolation valves for selectively sealing a first region from a second region. A gate valve can include a housing which defines a channel between the first and second regions. The valve includes a gate, located in the housing, and displaceable between a stowed position and a deployed position. When the gate is in the stowed position, communication is permitted between the first and second regions. When the gate is in the deployed position, the gate spans the channel and can be controlled to isolate the first and second regions. The valves can be used, for example, in connection with systems for processing large glass substrates. The valves are particularly useful for isolating long rectangular openings, such as the openings in substrate processing chambers. Isolating processing chambers or load lock chambers from one another, for example, in a linear system, is facilitated.

This is a continuation of application Ser. No. 09/082,376 filed May 20,1998 now U.S. Pat. No. 6,079,693.

RELATED APPLICATIONS

The present application is related to U.S. Pat. No. 6,235,634, issuedMay 22, 2001, and entitled “Modular On-Line Processing System,” as wellas the following U.S. patent: (1) “Method and Apparatus for SubstrateTransfer and Processing” U.S. Pat. No. 6,213,704issued Apr. 10, 2001;(2) “Multi-Function Chamber For A Substrate Processing System,”; U.S.Pat. No. 6,086,362, issued Jul. 11, 2000; (3) “An Automated SubstrateProcessing System,”; U.S. Pat. No. 6,215,897, issued Apr. 10, 2001; (4)“Substrate Transfer Shuttle Having a Magnetic Drive,”; U.S. Pat. No.6,206,176, issued Mar. 27, 2001; (5) “Substrate Transfer Shuttle,”; U.S.Pat. No. 09/082,484, filed May 20, 1998; (6) “In-Situ Substrate TransferShuttle,”; U.S. Pat. No. 6,176,668, issued Jan. 23, 2001; and (7)“Modular Substrate Processing System”. U.S. Pat. No. 08/946,922.

The foregoing patent applications, which are assigned to the assignee ofthe present application, are incorporated herein by reference in theirentirety.

BACKGROUND

The present invention relates generally to substrate processing systems,and, in particular, to isolation valves for substrate processingsystems.

Glass substrates are being used for applications such as active matrixtelevision and computer displays, among others. Each glass substrate canform multiple display monitors each of which contains more than amillion thin film transistors.

The processing of large glass substrates often involves the performanceof multiple sequential steps, including, for example, the performance ofchemical vapor deposition (CVD) processes, physical vapor deposition(PVD) processes, or etch processes. Systems for processing glasssubstrates can include one or more process chambers for performing thoseprocesses.

The glass substrates can have dimensions, for example, of 550 mm by 650mm. The trend is toward even larger substrate sizes, such as 650 mm by830 mm and larger, to allow more displays to be formed on the substrateor to allow larger displays to be produced. The larger sizes place evengreater demands on the capabilities of the processing systems.

Some of the basic processing techniques for depositing thin films on thelarge glass substrates are generally similar to those used, for example,in the processing of semiconductor wafers. Despite some of thesimilarities, however, a number of difficulties have been encountered inthe processing of large glass substrates that cannot be overcome in apractical way and cost effectively by using techniques currentlyemployed for semiconductor wafers and smaller glass substrates.

For example, efficient production line processing requires rapidmovement of the glass substrates from one work station to another, andbetween vacuum environments and atmospheric environments. The large sizeand shape of the glass substrates makes it difficult to transfer themfrom one position in the processing system to another. As a result,cluster tools suitable for vacuum processing of semiconductor wafers andsmaller glass substrates, such as substrates up to 550 mm by 650 mm, arenot well suited for the similar processing of larger glass substrates,such as 650 mm by 830 mm and above. Moreover, cluster tools require arelatively large floor space.

Similarly, chamber configurations designed for the processing ofrelatively small semiconductor wafers are not particularly suited forthe processing of these larger glass substrates. The chambers mustinclude apertures of sufficient size to permit the large substrates toenter or exit the chamber. Moreover, processing substrates in theprocess chambers typically must be performed in a vacuum or under lowpressure. Movement of glass substrates between processing chambers,thus, requires the use of valve mechanisms which are capable of closingthe especially wide apertures to provide vacuum-tight seals and whichalso must minimize contamination.

Furthermore, relatively few defects can cause an entire monitor formedon the substrate to be rejected. Therefore, reducing the occurrence ofdefects in the glass substrate when it is transferred from one positionto another is critical. Similarly, misalignment of the substrate as itis transferred and positioned within the processing system can cause theprocess uniformity to be compromised to the extent that one edge of theglass substrate is electrically non-functional once the glass has beenformed into a display. If the misalignment is severe enough, it even maycause the substrate to strike structures and break inside the vacuumchamber.

Other problems associated with the processing of large glass substratesarise due to their unique thermal properties. For example, therelatively low thermal conductivity of glass makes it more difficult toheat or cool the substrate uniformly. In particular, thermal losses nearthe edges of any large-area, thin substrate tend to be greater than nearthe center of the substrate, resulting in a non-uniform temperaturegradient across the substrate. The thermal properties of the glasssubstrate combined with its size, therefore, makes it more difficult toobtain uniform characteristics for the electronic components formed ondifferent portions of the surface of a processed substrate. Moreover,heating or cooling the substrates quickly and uniformly is moredifficult as a consequence of its poor thermal conductivity, therebyreducing the ability of the system to achieve a high throughput.

In the past, a variety of isolation valves have been used to isolate tworegions from one another. In an exemplary construction, a gate slidesinto and out of a path, transversely to the path, to open and close thevalve. With the gate in a closed position, a seal can be formed betweenthe gate and a valve seat to prevent flow through the valve. Slidevalves offer particular compactness, in other words, a small size asmeasured in a direction along the flow path.

One recently proposed system for processing large glass substrates is amodular in-line processing system, such as the system described in thepreviously mentioned U.S. patent application Ser. No. 08/946,922. Such asystem can be used for CVD or other thermal substrate processing and caninclude multiple back-to-back processing chambers through which asubstrate is transferred. The process chambers typically are operatedunder vacuum or under very low pressure. Thus, there is a relativelyuniform pressure distribution between the chambers which is insufficientby itself to provide the required tight seal between the gate and thevalve seat.

SUMMARY

In general, the invention discloses various improved isolation valves.According to one aspect, an isolation valve for selectively sealing afirst region from a second region includes a housing. The housingdefines a channel between the first region and the second region, andthe channel extends at least between a first port and a second port. Thevalve also includes a gate disposed within the housing. The gate isdisplaceable between a stowed position in which communication ispermitted between the first region and the second region, and a deployedposition in which the gate spans the channel.

The gate includes first and second sealing members, each of which has arespective outward-facing surface. Further, the gate has an expandablemember disposed between the first sealing member and the second sealingmember, wherein the expandable member is expandable from a firstcondition to a second condition and can be contracted from the secondcondition to the first condition.

In the first condition, the gate is moveable between the stowed anddeployed positions. In the second condition, with the gate in thedeployed position, the first and second sealing members are biased apartfrom each other by expansion of the expandable member so that theoutward-facing surface of the first sealing member is sealingly engagedto the first port so as to seal the first region from the second region.The outward-facing surface of the second sealing member is engaged tothe housing.

In some implementations, such as where two or more processing chambersare positioned back-to-back, both sealing members engage theirrespective ports to seal the first region from the second region.

In various implementations, the expandable member can include a bellowsor an inflatable member, such as an elastomeric bladder.

In another aspect, an isolation valve includes a housing defining achannel between a first chamber and a second chamber and a gate assemblydisposed within the housing. The valve also includes means forpositioning the gate assembly between a first port in communication withthe first chamber and a second port in communication with the secondchamber. Additionally, the valve has means for causing the gate assemblyto engage the first port so as initially to seal the first chamber fromthe second chamber. Furthermore, the valve has means for altering apressure within the housing to further seal the first chamber from thesecond chamber. A method of sealing a first chamber from a secondchamber also is disclosed.

In an alternative embodiment, an isolation valve includes a housinghaving a passageway through which a substrate can be transferred. Asurface along a perimeter of the passageway forms a seat for engaging agate. The valve also includes a gate disposed within the housing,wherein the gate has a first position in which the passageway is openand a second position in which the gate engages the seat to seal thepassageway. The valve also has a lift mechanism coupled to the gate forcontrolling movement of the gate between its first position and anintermediate position opposite the passageway. The valve also includes arotating mechanism coupled to the gate for controlling movement of thegate between its intermediate position and its second position.

When the gate is in its second position, a horizontal force componentcan be provided to seal the gate against the passageway. In oneimplementation, the rotating mechanism includes one or more pushcylinders each having respective first and second positions. Movement ofthe push cylinders between their first and second positions causes thegate to rotate between its intermediate raised position and its secondposition in which the passageway is sealed.

In various implementations, two or more substrate processing chamberscan be positioned back-to-back. A double-sealing isolation valve orindependently controllable isolation valves can be provided between thechambers to seal them, for example, during processing.

The valve housings can be formed separately from the chambers andsubsequently secured in place. Alternatively, the valve housings can beformed as a single integral unit with a chamber.

Among the advantages of a valve according to the present invention isdesign flexibility. For example, in the laboratory or industrialsetting, the valve can be used as a door or gate through which glasssubstrates or other items may pass. In such situations, it isadvantageous to select a valve geometry (size, cross-sectional profile,etc.) to accommodate the items passing through the valve as well as anyother environmental factors. This is preferable to having to conform theitems or processes by which they are manipulated to geometries and sizesof available valves.

By way of example, in the manufacture and processing of flat objectssuch as glass substrates for flat panel displays, processing chambersmay be used which have a relatively low profile, in other words, a smallheight and large width. Space efficiency considerations indicate thatthe valves sealing such chambers need only have a similarly low profileto accommodate the ingress and egress of the items.

The use of an inflatable member to separate the valve plates can providea more even distribution of the sealing force between the valve platesthan in a purely mechanical system. Thus, in the case of an elongatedgate, the sealing force can be distributed substantially continuouslyalong the gate. However, whatever the desired gate profile, anappropriate inflatable chamber can be configured easily and can usestock inflation equipment. This feature provides cost savings byreducing the need for multiple complex mechanical linkages specificallyconfigured for each gate profile.

Another advantage is the ability to accommodate the valve to less thanperfect valve seats. The inflatable member has significant flexibilityand, therefore, can create an adequate seal despite a loss ofparallelism, changes in seat separation, or even loss of flatness. Witha mechanically-actuated valve, wear or contamination of the seatingsurfaces may greatly alter the forces applied to the plates. With theinflation member, the force is simply related to the pressure applied tothe chamber. Performance is less sensitive to wear except in the extremecase of a rupture or leak.

Additionally, to compensate for the lack of ability of the cammingmechanism to accommodate changes or irregularities in the seats and toaccommodate for the effect of wear of the camming mechanism, a highlycompressible flexible seal may be utilized with a cam-type valve. Such aseal will necessarily undergo a relatively high deformation andtherefore may be subject to wear or failure. With the present invention,the chamber can provide a significant degree of compliance so that thesame compliance need not be present in the seals. Therefore, the sealsare subjected to less deformation. The wearing of the mechanicallinkages also can create contaminant particles which can interfere withthe operation of the valve or the operation of any enclosure the valveis used to seal and contaminate any fluid passing through the valve.

In alternative implementations, mechanical isolation valves aredisclosed that are particularly suited for modular systems in whichmultiple chambers are aligned adjacent one another. Each chamber can beprovided with passageways at opposite sides of the chamber. Thepassageways, which can be used for transferring a substrate into or outof the chamber, can be opened or sealed by respective gates which arecontrolled independently of one another, thereby providing additionalflexibility. The mechanical isolation valves are compact and have arelatively simple construction, thereby helping to reduce manufacturingcosts.

The mechanical valves also can provide an improved means for sealing onechamber from another chamber and help prevent cross-contamination fromprocess gases used in the various chambers. The mechanical rotation ofthe gate toward the passageway creates the seal and provides lateralpressure to improve the seal that is required when processing glasssubstrates.

When two chambers are aligned adjacent one another, the area between thechambers can be isolated from either one or both of the chamberinteriors effectively forming a buffer chamber. The area between thechambers can, therefore, be protected, for example, from process gases,some of which may be corrosive. By isolating the area between thechambers from the chamber interiors, other components of the systemexternal to the processing chambers can be protected from contact withcorrosive gases or other harmful materials used within the chambersduring substrate processing. Additionally, the pressure of the areabetween the chambers can be controlled independently of the pressures ineither one or both of the chamber interiors.

Other features and advantages will be apparent from the detaileddescription, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a transverse cross-sectional view of a valve, shown in an openconfiguration, according to one implementation of the invention.

FIG. 2 is a partial longitudinal cross-sectional view of the valve ofFIG. 1, taken along line 2—2.

FIG. 3 is a top cross-sectional view of the valve of FIG. 2, taken alongline 3—3.

FIG. 4 is a transverse cross-sectional view of the valve of FIG. 1,shown in a closed configuration.

FIG. 5 is a partial longitudinal cross-sectional view of the valve ofFIG. 4, taken along line 5—5.

FIGS. 6 and 7 are partial transverse cross-sectional views of valvesaccording additional implementations of the invention.

FIG. 8 is a partial elevated view of a chamber according to yet anotherimplementation of the invention.

FIG. 9 is a side view of the chamber of FIG. 8 with actuator housings.

FIG. 10 is a side view of the chamber of FIG. 8 showing a lift mechanismin a lowered position.

FIG. 11 illustrates a rod block which forms part of the lift mechanismin FIG. 10.

FIG. 12 is a side view of the chamber of FIG. 8 showing the liftmechanism in a raised position.

FIG. 13 is a side view of the lift mechanism taken along line 13—13 inFIG. 12.

FIG. 14 is a side view of the lift mechanism taken along line 14—14 inFIG. 12.

FIGS. 15A-15C illustrate the sealing plate between a lowered position, araised position and a closed position, respectively.

FIGS. 16-17 are partial elevated side views of the chamber of FIG. 8with a sealing plate positioned in lowered and raised (or closed)positions, respectively.

FIG. 18 is a partial elevated side view of the chamber of FIG. 16including a drive mechanism for a substrate transfer shuttle.

FIG. 19 illustrates two chambers positioned adjacent one anotheraccording to the invention.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, a valve 10 includes a housing 12, a gate 14and an actuator 16. The housing 12 has an interior bounded by first andsecond vertically-extending sides 18A and 18B, a top 20, a bottom 22,and ends 24A, 24B. In general, the valve can be used, for example, toisolate one process chamber from another process chamber, or to isolatedifferent regions from one another.

The housing defines a passageway 28 which extends along a path throughthe housing from an inlet 30 to an outlet 32. In variousimplementations, the roles of the inlet 30 and outlet 32 can be reversedsuch that a substrate can travel in either direction through the valve.The channel has a longitudinal axis 200. The inlet 30 and outlet 32extend transverse to the axis 200 and are elongate and generallyrectangular in shape. First and second regions or chambers 202, 204 arelocated adjacent the inlet 30 and outlet 32, respectively. An externalregion is shown generally as 206. In the exemplary embodiment, thehousing 12 is generally symmetric about a vertical transverse centerplane 208.

With the valve in an open condition, as shown in FIGS. 1 and 2, the gate14 is in a lowered or stowed position, residing in a bay 34 of thehousing. The gate 14 has first and second sealing members, such assealing plates 36A, 36B, respectively (FIG. 2). Each sealing plate 36A,36B has a longitudinally outboard plate 38A, 38B, and a longitudinallyinboard plate 40A, 40B. Each outboard plate 38A, 38B is held flatagainst the associated inboard plate 40A, 40B such as by means ofcounter-bored screws 42. The outboard faces 44A, 44B of outboard plates38A, 38B face the regions 202, 204, respectively, and each bears agenerally rectangular slot in which a gasket 48A, 48B is carried. Theinboard faces 46A, 46B of inboard plates 40A, 40B face toward theregions 204, 202, respectively, and form inboard faces of the sealingplates 36A, 36B, respectively.

Flexures or leaf springs 50A, 50B depend from the lower edges of thesealing plates-36A, 36B, respectively. Each flexure 50A, 50B is attachedat its upper edge 52A, 52B to the lower edge of the associated inboardplate 40A, 40B. The bottom end 54A, 54B of each flexure 50A, 50B issecured to a transversely-extending cross-member 60 of a frame 62 (FIG.1).

The frame 62 further includes a pair of posts or uprights 64A, 64B(FIG. 1) extending upwardly from the cross-member 60 at opposite ends ofthe cross-member. Extending along the laterally outboard faces of theuprights 64A and 64B, respectively, are a pair of outwardly facingchannel members 66A, 66B. The channel members are of open rectangularsection.

At opposite sides of the housing, pairs of upper and lower low frictionguides 68A, 68B extend inwardly from respective sides 18A, 18B. Theguides are accommodated within the associated channel members 66A, 66Bso as to allow the channel members and gate 14 to slide verticallybetween the open position shown in FIGS. 1 and 2 and a closed positionshown in FIGS. 4 and 5.

Referring to FIG. 3, an expandable chamber or volume 80 which can beinflated is disposed within the housing. The chamber 80 is bounded by anexpandable member, such as an inflatable elastomeric bladder 82 or abellows, which is positioned between the sealing plates 36A and 36B. Inthe illustrated embodiment, the bladder 82 is continuous andsubstantially laterally coextensive with the sealing plates 36A, 36B,being slightly recessed from upper, lower and lateral edges of theplates. The bladder has an inner surface 84 surrounding the chamber 80and an outer surface 86 which engages the inboard faces 46A, 46B of thesealing plates.

On each side of the gate 14, center blocks 90A, 90B (see also FIG. 1)are rigidly affixed to the associated uprights 64A, 64B and extendlaterally inward slightly beyond the lateral edges of the sealing plates36A and 36B. Contact between the inboard faces 46A, 46B of the sealingplates 36A, 36B and the adjacent sides 92A, 92B of the blocks restrictsinward longitudinal movement of the sealing plates.

Above and below each center block 90A, 90B is a centering mechanism 100(FIGS. 1 and 3). Each centering mechanism 100 includes a first pin 104A(FIG. 3) extending laterally outward from the associated side of thesealing plate 36A and a second pin 104B extending laterally outward fromthe associated side of the sealing plate 36B. A coil-type tension spring106 connects the first pin 104A to the second pin 104B. Thus,collectively, the springs 106 of the centering mechanisms 100 bias thetwo sealing plates 36A, 36B toward each other and, thus, toward thetransverse vertical center plane 208.

In an alternate embodiment shown in FIG. 6, each centering mechanismcomprises a center pin 102 extending laterally inward from an associatedupright 64A, 64B. An upstream coil-type tension spring 106A connects thefirst pin 104A to the center pin 102, and a downstream coil-type tensionspring 106B connects the second pin 104B to the center pin 102. Thesprings 106A, 106B bias the sealing plates 36A, 36B toward thetransverse vertical center plane 208.

Returning to FIG. 3, an inflation/deflation conduit 110 extends throughthe bladder 82 into the chamber 80. The conduit 110 can be directedbetween the flexures 50A, 50B and out through the actuator 16 to aremote source 112 (FIG. 1). In the exemplary embodiment, the source 112can take the form of an appropriate pump along with the associatedvalves and control systems for selectively introducing a gas into thechamber 80 through the conduit 110 and withdrawing the gas from thechamber through the conduit 110 to inflate and deflate the chamber. Aconduit 114 (FIG. 1) extends through the housing into the cavity 34. Theconduit 114 is connected to a source 116 which may be similar to asource 112. The source 116 facilitates the selective pressurization anddepressurization of the housing external to the chamber 80.

To close the valve, the actuator 16 is controlled to raise the gate 14from the lowered or stowed position (FIGS. 1 and 2) to a raised ordeployed position (FIGS. 4 and 5). In the deployed position, the sealingplates 36A, 36B are aligned with and facing the inlet and outlet ports30, 32, respectively. Valve seats 120A, 120B are formed in the housingsurrounding the inlet and outlet ports 30, 32, respectively. The valveseats have seating faces 122A, 122B facing generally toward the regions204, 202, respectively. The seating faces 122A, 122B respectively faceand are aligned with the gaskets 48A, 48B when the gate 14 is in thedeployed position.

With the gate 14 in the deployed position, the chamber 80 is inflated orpressurized, producing longitudinal outward forces on the sealing plates36A, 36B. When the pressure in the chamber 80 is sufficient, it willovercome the tension in the springs 106 and drive the sealing plates36A, 36B longitudinally outward to place the gate 14 in an expandedcondition. The longitudinally outward movement of the sealing plates36A, 36B brings the gaskets into sealing engagement with the seatingfaces 122A and 122B, respectively (FIG. 5). In this way, the sealingplates 36A, 36B become sealingly engaged to the seats 122A, 122B of therespective inlet and outlet ports 30, 32 to prevent fluid flow throughthe ports. In this manner, the regions or chambers 202, 204 can beisolated from one another as well as from the passageway 28 in the valvehousing.

To open the valve, the chamber 80 is deflated or depressurized, reducingthe longitudinally outward forces on the sealing plates 36A, 36B. Whenthe pressure in the chamber 80 is sufficiently reduced, the tension inthe springs 106 overcomes the pressure difference across the respectiveplates 36A, 36B and overcomes any sticking of the gaskets 48A, 48B so asto disengage the sealing plates and gaskets from the seats 122A, 122B.Although the chamber 80 can be depressurized by venting to atmosphere, avacuum may be applied to the chamber by the source 112 so that reducedpressure further assists the springs 106 to draw the plates together.With the chamber 80 returned to the unexpanded condition, the actuator16 is controlled to lower the gate 14 from the deployed position to thestowed position, thereby clearing the channel 28.

Exemplary materials used in construction of the valve 10 includealuminum for the housing 12 and the plates 36A, 36B, although stainlesssteel can be used if there is to be exposure to chemicals which reactwith aluminum. The gaskets 48 can be formed of a flouroelastomer such assold under the trademark VITON by E.I. du Pont de Nemours and Company.The gaskets 48 are secured in their associated grooves via bondingadhesive or via forming the grooves with a dovetail or similar profileto capture the gaskets. The flexures 50A, 50B can be formed of stainlesssteel sheets.

The dimensions of the valve 10 can be selected based on the particularapplication in which it is to be used. An exemplary application involvesthe sealing of chambers used in large glass substrate processing (e.g.,separating a load lock chamber from a process chamber). For such anapplication the valve can be configured to accommodate passage ofsubstrates between the chambers. In an exemplary embodiment suitable forlarge glass substrates, such as substrates having an area of one squaremeter, the ports 30, 32 are about 5-6 inches high and about 50 incheswide. The plates 36A, 36B can be approximately 1 inch greater in widthand height than the ports 30, 32, and the bladder 82 approximately 0.5inches greater in width and height than the ports.

When both plates are sealingly engaged to their respective ports, thepressure in the housing can be greater than the pressure in an adjacentprocessing chamber. The pressure in the housing can be at ambientpressure.

Furthermore, the ability to pressurize and depressurize the housing 12external to the chamber 80 provides a number of options to the user.With a pressure in the chamber 80 designated P₃ (controlled via thesource 112), and an ambient pressure designated P_(A), a pressure P₄ inthe housing can be controlled relative to any of P_(A), P₃, andpressures P₁ and P₂ in the regions 202 and 204, respectively. In oneoption which is particularly useful when the difference between P₁ andP₂ is large, the housing 12 and io chamber 80 can be pressurizedsimultaneously. Since the strength of the bladder 82 limits the amountby which P₃ may exceed P₄, the more P₄ is increased, the more P₃ may beincreased so as to increase the sealing force. Furthermore, to theextent that the chamber 80 does not cover the entire area of the gate14, the force applied by the pressure P₄ to those areas of the gatebeyond the chamber will help seal the valve. This may be particularlyuseful where multiple discrete chambers, such as those formed by metalbellows are utilized. In a situation where the valve is used to seal alow pressure processing chamber from a higher pressure chamber orregion, it may be particularly desirable to prevent contamination. Insuch a situation, a vacuum can be applied to the housing 12 to reducethe pressure P₄ so that any gas leaking from the high pressure chambercan be evacuated through the conduit 114.

FIG. 7 shows an alternate valve having one sealing plate 36B′ whichgenerally is similar to the plates the 36A, 36B in FIGS. 1-6. In anexemplary application, an inlet 30′ is coupled to a low pressure chamberwhich can be pressurized with inert gas. A second port 32′ can beconnected to a process chamber for low pressure processing in a reactantgas environment. The inert gas can flow through holes 37 in the plate36A′ to fill the housing. The pressure from the inert gas can augmentthe sealing in a similar fashion to the housing pressurization describedabove.

The use of an inflatable chamber 80 to separate the valve plates 36A,36B and seal the valve 10 provides a significant degree of flexibilityin valve design. The force (pressure distribution) separating the plates36A, 36B can be distributed more evenly than in a purely mechanicalsystem. For example, the force can be distributed substantiallycontinuously along an elongate gate member. Valves as described andillustrated in FIGS. 1-7 can offer savings in cost, weight, size, andcomplexity.

Various modifications can be made to the implementations describedabove. For example, although in the illustrated embodiment the chamber80 is formed by a generally rectangular continuous elastomeric bladder82, one or more bladders of other geometries may be used. The chamber 80can be formed other than by an elastomeric bladder, such as by one ormore bellows. In general, the chamber 80 includes an expandable memberwhich can be expanded from a first condition to a second condition andwhich can be contracted from the second condition to the firstcondition. In the first condition, the gate is moveable between thestowed and deployed positions, and in the second condition, with thegate in the deployed position, the first and second sealing members arebiased apart from each other by expansion of the expandable member sothat the outward-facing surface of at least one sealing member issealingly engaged to a respective one of the ports so as to seal thefirst region from the second region.

Additionally, although the valve illustrated in FIGS. 1-6 issubstantially symmetric about its transverse central plane, asymmetricvalves also can be provided. Various actuators and gate geometries maybe used and many specific properties of the valve may be influenced ordictated by the particular application for which the valve is designatedor adapted.

In the implementations described above with respect to FIGS. 1-6, thesealing plates 36A, 36B are controlled substantially simultaneously toengage their respective seats 122A, 122B and to isolate the regions 202,204.

In contrast to the foregoing description, as an alternative embodiment,FIGS. 8-19 illustrate a substrate chamber with mechanical isolationvalves. The implementations described below allow passageways inadjacent chambers to be sealed independently of one another. Moreover,the valves described below include mechanically actuated gates whichprovide a horizontal force component to enhance the seal between thegate and the valve seat.

Referring to FIGS. 8-9, a chamber 300, such as a chemical vapordeposition.(CVD) or other substrate processing chamber, includes a frame302, having sidewalls 301A-301D, a top 303A and a bottom 303B. The valvehousings 304A, 304B are integrally formed with the sidewalls 301A, 301Bof the chamber 300 so that the valve housings and the chamber form asingle unit. The valve housings also can be formed separately and thenbolted or otherwise attached to the chamber. As discussed in greaterdetail below, the valve housing 304B is wider than the valve housing304A in a direction parallel to the chamber sidewalls 301C, 301D.

An opening or passageway 312B is formed in the sidewall 301B of thechamber 300. Another opening or passageway 312A is formed in theopposite sidewall 301A. The dimensions of the passageways 312A, 312B canbe selected to allow a substrate to be transferred in and out of thechamber 300 through the passageways. An outward-facing surface along theperimeter of the passageway 312B forms a seat 314B for engaging anassociated gate 310B, and a similar seat is formed by an outward-facingsurface along the perimeter of the passageway 312A to engage anassociated gate 310A. The respective surfaces that form the seats, suchas the seat 314B, face away from the interior of the chamber 348. Thegates 310A, 310B can be formed as sealing plates. In one implementation,the sealing plates 310A, 310B have a length of approximately 50 inches,and a height of approximately 5-6 inches. Such an implementation issuitable for large glass substrates on the order, for example, of onesquare meter. Each valve housing 304A, 304B has an open side oppositethe respective passageways 312A, 312B.

Reinforcement members 316A, 316B can be provided above the valvehousings 304A, 304B to reinforce the chamber frame 302. Respectiveactuator housings, or frames, 306A, 306B are bolted or otherwise securedto the chamber 300 below the valve housings 304A, 304B. The actuatorhousings 306A, 306B provide stiffness for the chamber 300. The actuatorhousing 306A and the valve housing 304A are configured so that theactuator housing extends slightly beyond the valve housing in adirection parallel to the sidewalls 301C, 301D and away from the chamberinterior 348. Similarly, the actuator housing 306B and the valve housing304B are configured so that the valve housing extends slightly beyondthe actuator housing in a direction parallel to the sidewalls 301C, 301Dand extending away from the chamber interior 348. Such an asymmetricconfiguration allows multiple chambers to be aligned adjacent oneanother as discussed further below with respect to FIG. 19.

Each actuator housing 306A, 306B contains a respective actuator 307A;307B. Each actuator 307A, 307B includes a respective lift mechanism308A, 308B for lifting and lowering an associated one of the gates 310A,310B disposed within the valve housings.304A, 304B. Each actuatorhousing 307A, 307B also includes a respective rotating mechanism 309A,309B coupled to an associated one of the lift mechanisms 308A, 308B, aswell as coupled to as associated one of the gates 310A, 310B.

Each lift mechanism 308A, 308B can be raised from a first loweredposition to an intermediate or raised position. The lift mechanisms308A, 308B also can be rotated from the intermediate raised position toa second closed position by actuating the associated rotating mechanism309A, 309B. In the closed position, the gates 310A, 310B engage theirrespective seats 314A, 314B and seal the chamber 300 from the valvehousings 304A, 304B. When the gate is in its second closed position, ahorizontal force component is provided to seal the gate against thepassageway.

The lift mechanisms 308A, 308B also can be returned to their respectivelower positions. Moreover, the lift mechanisms 308A, 308B can becontrolled independently of one another. As shown in FIG. 9, the liftmechanism 308B is in the first (lowered) position, and the gate 310Bdoes not engage its seat. The lift mechanism 308A, however, is shown inits raised position with the rotating mechanism 309A actuated so thatthe gate 310A engages the seat 314A (FIG. 8) and seals the chamber 300from the housing 304A.

Referring to FIG. 10, each lift mechanism, such as the lift mechanism308B, includes a central lift cylinder 318 mounted to a pivot plate 328.The lift cylinder 318, which has a piston rod 319 extending verticallythrough its major axis, is coupled to a lift plate 320. The lift plate320 includes substantially horizontal sections 321 that extend laterallyoutward. A respective rod block 322 is coupled to the lift plate 320 ateach of its laterally extending ends 321. Each rod block 322 hasmultiple cam followers or wheels 324 which allow the rod block 322 toslide vertically up or down along stationary vertical slots 326 disposedwithin the housing 306B. The lower section of each rod block 322includes a vertical slot 340 (FIG. 10) whose function is explainedbelow.

As shown in FIGS. 10-11, each rod block 322 carries a vertical shaft330, the lower end of which extends at least partially into the rodblock 322 in a fixed position and is substantially parallel to the majoraxis of the rod block 322. The upper end of each shaft 330 extendsthrough a respective compressible bellows 332 and is coupled at itsupper end to the gate 310B (not shown in FIG. 10). The bellows 332 helpmaintain the pressure or vacuum as the shafts 330 are moved upward ordownward. The gate or sealing plate 310B is offset slightly with respectto the vertical axis 331 of the shaft 330 (FIG. 15A). A sphericalalignment joint 358 (FIG. 19) helps provide the desired alignmentbetween the sealing plate 310B and the seat 314B. In the illustratedimplementation, the sealing plate 310B and the vertical axis 331 of theshaft 330 form an angle x of at least 0.5 degrees, for example,approximately 1.3 degrees (FIG. 15A). In some implementations, however,the angle x can be less than 0.5 degrees yet greater than 0 degrees.

In one implementation, the rotating mechanism 309B includes at least onepush cylinder 334 coupled to a push plate 336 by spherical rod ends 342(see FIGS. 10, 12 and 14). The illustrated implementation includes apair of push cylinders 334. Distal ends of the push plate 336 arecoupled to low friction cam followers or wheels 338. To maintain thedesired orientation of the push plate, the push plate 336 is coupledto′a total of three cam followers 338. When the rod blocks 322 are movedvertically upward or downward, the vertical slot 340 disposed within thelower section of each rod block 322 slides along the cam followers 338which remain substantially stationary.

When the lift cylinder 318 is in its first or lowered position (FIGS. 10and 15A), the sealing plate 310B is positioned slightly lower than thepassageway 312B between the interior 348 of the chamber 300 and thevalve housing 304B (FIG. 15A). In this first lowered position, the topof the sealing plate 310B is displaced slightly outward from the lowerportion of the seat 314B. As noted above, in the illustratedimplementation, the sealing plate 310B is offset slightly from thevertical axis 331 of the shaft 330 as well as from the vertical axis 313of the seat 314B.

The lift cylinder 318 can be controlled to move the sealing plate 310Bfrom the lower position to the raised intermediate position opposite thepassageway 312B to the chamber 300. In particular, the lift cylinder 318causes the piston rod 319 to move vertically upward (FIGS. 12-13).Upward movement of the piston rod 319 lifts the entire lift plate 320and the attached rod blocks 322 upward. Upward movement of the rodblocks 322 lifts the shafts 330 upward, thereby moving the sealing plate310B to the raised position opposite the passageway 312B (FIG. 15B). Inthis intermediate raised position, the sealing plate 310B is not yetsealed against the seat 314B, and the top of the sealing plate tiltsaway from the passageway 312B.

To seal or close the passageway 312B, air pressure in the push cylinders334 is reversed to move the push cylinders from respective first orextended positions to respective second or contracted positions. As thecylinders 334 move to their contracted positions, the push plate 336moves slightly outward away from the chamber 300. The lateral outwardmovement of the push plate 336 causes′the lift plate 320, the rod blocks322 and the shafts 330 to rotate slightly so that the sealing plate 310Bis moved flush against the seat 314B surrounding the passageway 312B(FIG. 15C). Specifically, in the illustrated implementation, the sealingplate 310B is rotated approximately 1.3 degrees, thereby moving thesealing plate to its second or closed position and sealing the chamberpassageway 312B. When the sealing plate 310B is flush against the seat314B, fluid communication between the chamber interior 348 and theinterior of the valve housing is prevented through the passageway 312B.

To unseal or open the passageway 312B and move the sealing plate 310B toits lowered position, the procedure described above is reversed. The airpressure in the push cylinders 334 again is reversed to move the pushcylinders to their respective extended positions. In someimplementations, the pressure of the push cylinders 334 is changedsubstantially simultaneously. In other implementations, particularlywhen the seal created between the sealing plate 310B and the seat 314Bis tight, the pressure of one push cylinder 334 can be changed prior tochanging the pressure of the other push cylinder. As the seal isloosened, the sealing plate 310B rotates back to its raised intermediateposition in which the sealing plate is opposite, but not in contactwith, the seat 314B (FIG. 15B). The lift cylinder 318 then can becontrolled to bring the sealing plate 310B to its lower position inwhich the top of the sealing plate 310B is opposite the lower portion orbottom of the seat 314B (FIG. 15A). In other words, the top of thesealing plate 310B can be substantially at least as low as the bottom ofthe passageway 312B. The sealing plate 310B remains disposed within thevalve housing 304B even when the sealing plate is in the lower position(FIG. 16).

The sealing plate 310A and the actuator 307A operate in substantiallythe same manner as the sealing plate 310B and the actuator 307B.

In some implementations, the sealing plate 310B need not be offset fromthe vertical axis 331 of the associated shaft 330. Rather, the sealingplate 310B and the associated shaft 330 can be substantially parallel toone another. In such an implementation, when the lift mechanism 308B isin its lowered position, the sealing plate 310B, as well as theassociated shaft 330, is slightly offset from the vertical axis of the313 of the seat 314B such that the top of the sealing plate tilts awayfrom the seat. Once the lift mechanism 308B is moved to its intermediateraised position, the push cylinders 334 cause the sealing plate 310B andthe shaft to rotate so as to move the sealing plate to its closedposition, thereby sealing the chamber passageway 312B. When the gate310B is in its closed position, the sealing plate 310B, the associatedshaft 330 and the vertical axis of the seat 314B are substantiallyparallel to one another.

Referring again to FIG. 8, each of the valve housings 304A, 304Bincludes openings 344 that are substantially perpendicular to thepassageways 312B, 312A in the interior 348 of the chamber 300. Theopenings 344 are configured such that when the sealing plate 310B (or310A) is in its raised position, the openings 344 in the valve housing304B are substantially parallel to the width of the sealing plate (FIG.17). The dimensions of the openings 344 are configured to be slightlylarger than a cross-section of the sealing plates 310A, 310B so that thesealing plates can be removed from their respective housings 304A, 304Bvia the openings for maintenance or inspection. The valve housings 304A,304B also have one or more openings 346 through their respective topsurfaces. The openings 346 aid visual inspection of alignment of thesealing plates 310A, 310B, as well as the removal of the sealing platesand other maintenance functions.

As noted above, the valve housing 304B is somewhat wider than the valvehousing 304A in a direction parallel to the chamber sidewalls 301C,301D. Referring to FIGS. 8 and 18, the valve housing 304B includes oneor more openings 352 which serve as a vacuum feed through for a drivemechanism 350 of a substrate transfer shuttle or other substratetransfer mechanism (not shown) that transfers substrates between processchambers. In the illustrated implementation, the opening 352 is locatedadjacent one of the openings 344, and the drive mechanism 350 isdisposed within the valve housing 304B. Further details of an exemplarydrive mechanism 350 and substrate transfer shuttle are described in thepreviously mentioned U.S. application Ser. No. 09/082,428 entitled“Method and Apparatus for Substrate Transfer and Processing”.

As shown in FIG. 19, a first chamber 300′ and a second chamber 300″,each of which has a construction similar to that of the chamber 300, canbe aligned to permit a substrate to be transferred from one chamber tothe other and vice-versa. Features of the chambers 300′, 300″ aredesignated with reference numerals which identify similarly-numberedfeatures of the chamber 300. Thus, the first chamber 300′ has aninterior 348′, a valve housing 304B′, and an actuator housing 306B′. Thevalve housing 304B′ includes an opening 352′ to serve as a feed throughfor the drive mechanism of a substrate shuttle transfer. As shown inFIG. 19, the sealing plate 310B′ is in its lowered position. Similarly,the second chamber 300″ has an interior 348″, a valve housing 304A″, andan actuator housing 306A″. As shown in FIG. 19, the sealing plate 310A″is in its raised position.

Due to the asymmetry between the respective valve housings 304B′, 304A″and the actuator frames 306B′, 306A″, the valve housing 304B′ of thefirst chamber 300′ partially extends over the actuator frame 306A′ ofthe second chamber 300″ when the chambers are positioned adjacent oneanother and coupled to one another. The construction of the chambers300′, 300″ increases the ease with which two or more chambers can becoupled together as part of a modular system having multiple chambers.The chamber construction also increases the overall compactness of thesystem.

When both sealing plates 310B′, 310A″ are in their respective lowerpositions, a substrate can be transferred from one chamber to the other.When both sealing plates 310B′, 310A″ are in their respective raised andsealed positions, the area between the two sealing plates is isolatedfrom the interiors 348′, 348″ of the chambers 300′, 300″, effectivelyforming a buffer chamber. The area between the sealing plates 310B′,310A″ is, therefore, protected, for example, from process gases, some ofwhich may be corrosive. By isolating the area between the sealing platesfrom the interiors of the chambers, the drive mechanism 350 associatedwith the substrate transfer shuttle can be protected from contact withcorrosive gases or other harmful materials used within the chambersduring substrate processing. Additionally, the pressure of the areabetween the sealing plates 310B′, 310A″ can be controlled independentlyof the pressures in the interiors 348′, 348″ of either or both of thechambers 300′, 300″. For example, the pressure in the area betweensealing plates 310B′, 310A′ can be controlled to increase the forceapplied by the sealing plates 310B′, 310A″ against the respective seats314B′, 314A″ to improve the seal created by the plates. Similarly, priorto unsealing the plates 310B′, 310A″, the pressure in the area betweenthe plates can be controlled to make it easier to unseal them from theirrespective seats 314B′, 314A″.

Other implementations are within the scope of the following claims.

What is claimed is:
 1. An isolation valve comprising: a housing defininga channel between a first port and a second port; and a gate disposedwithin the housing and displaceable between a stowed position in whichcommunication is permitted between the first port and the second port,and a deployed position in which the gate separates the first port fromthe second port, the gate including: (a) a first sealing member and asecond sealing member; (b) a first post and a first centering blockcoupled to the first post, and a second post and a second centeringblock coupled to the second post, the first and second centering blocksbeing disposed between the first sealing member and the second sealingmember; (c) at least one spring biasing the first sealing member and thesecond sealing member toward the first and second centering blocks; (d)an actuator that selectively moves the gate between the stowed anddeployed positions; (e) a frame that couples the actuator to the gate,the frame comprising a transverse cross-member coupled to the actuatorand having first and second ends, wherein the first and second posts arecoupled to the first and second ends of the cross-member, respectively;and (f) an expandable member disposed between the first and secondcentering blocks and the first sealing member and the second sealingmember, the expandable member being expandable from a first condition,wherein the gate is moveable between the stowed and deployed positions,to a second condition, wherein the gate is in the deployed position andthe first sealing member and the second sealing member are biased apartfrom each other by expansion of the expandable member so that the firstsealing member is sealingly engaged to the first port.
 2. The valve ofclaim 1, wherein the second sealing member is sealingly engaged to thesecond port in the second condition.
 3. The valve of claim 1, whereinthe first sealing member and the second sealing member are substantiallyaligned parallel to each other.
 4. The valve of claim 1, wherein theexpandable member comprises a bellows.
 5. The valve of claim 1, whereinthe first sealing member comprises a first gasket and the second sealingmember comprises a second gasket.
 6. The valve of claim 1, wherein fluidcommunication is blocked between the first port and the channel in thesecond condition.
 7. The valve of claim 1, wherein the gate blocks fluidcommunication between the first and second ports in the secondcondition.
 8. The valve of claim 1, wherein the first port and thesecond port each comprise an opening of about 50 inches wide and betweenabout 5 and about 6 inches high.
 9. The valve of claim 1, wherein eachof the first sealing member and the second sealing member comprises asubstantially flat plate.
 10. The valve of claim 9, wherein thesubstantially flat plate has a width of about 51 inches wide and aheight between about 6 and about 7 inches.
 11. The valve of claim 1,wherein the expandable member comprises an inflatable member.
 12. Thevalve of claim 11, wherein the expandable member comprises anelastomeric bladder.
 13. The valve of claim 1, wherein a plurality ofsprings bias the first sealing member and the second sealing membertoward the first and second centering blocks.
 14. The valve of claim 13,further comprising at least one pair of springs, wherein a first springin the pair couples the first sealing member to a centering mechanism,and a second spring in the pair couples the second sealing member to thecentering mechanism.
 15. The valve of claim 1, wherein the housingfurther comprises a conduit operatively coupled to a fluid source toallow pressurization and depressurization of the housing.
 16. The valveof claim 15, wherein the housing is vented to ambient pressure.
 17. Thevalve of claim 1, further comprising first and second flexures, eachflexure having an upper edge and a lower edge, wherein the lower edge ofthe first flexure is secured to the cross-member and the upper edge ofthe first flexure is secured to the first sealing member, and whereinthe lower edge of the second flexure is secured to the cross-member andthe upper edge of the second flexure is secured to the second sealingmember.
 18. The valve of claim 17, further comprising a first conduitfor inflating the expandable member, the first conduit being disposedbetween the first and second flexures.
 19. The valve of claim 18,further comprising a second conduit disposed between the first andsecond flexures for deflating the expandable member.